Perhaps the most influential figure in the sustainable agriculture movement is Joel Salatin, of Polyface Farms in Virginia. I'd also call him the most inspirational figure in that movement, because he has developed a working, profitable operation which integrates beef, pork, broilers, rabbits, and eggs. More than that, he takes in apprentices --- and travels the country giving speeches, helping others get started. As his website details, you can visit his farm and see how he puts all the pieces together. Some neighbors of ours did just that on a family vacation a couple of years ago, and said it was the highlight of their trip.
Joel has also written a number of books, a couple of which were among the first we read after moving here. They have proven invaluable.
In the next few days, I'll be putting up a post showing how we've incorporated his pastured poultry pens into our own farm.